From the earliest Quality VH guns I've recorded they are marked V above the serial number on the watertable --
89095 02.jpeg
That remains the way they were marked to at least 148672 --
148762 01 12-gauge, 30-inch, VH.jpg
By 151457 they moved the V below the serial number and put VH in an elongated hexagon above the serial number --
151457 01 VHE 28-inch.jpg
at some point between the 191xxx and 196xxx range the elongated hexagon disappears and it is just VH above and V below.